In the field of medicine, a patient may often require the administration of a pure supply of oxygen. For instance, infants born prematurely require extensive administration of oxygen since their lungs have incompletely formed.
Cannulas are used to deliver a stream of oxygen to the nasal passages of such patients. One style of a nasal cannula includes two nasal extensions which are inserted into the nostrils of the patient. For instance, U.S. Pat. No. 4,106,505 issued to Salter et al., U.S. Pat. No. 5,188,101 issued to Tumolo, and U.S. Pat. No. 5,271,391 issued to Graves all relate to nasal cannulas having invasive nasal extensions. A benefit of the invasive nasal extension is that substantially the entire oxygen stream is delivered to the nasal passages of the patient.
Several disadvantages are associated with the nasal cannulas having invasive nasal extensions. For example, the nasal extensions tend to dry out the nasal membranes of the patient, particularly patients who require extensive administration of oxygen, such as premature babies. The nasal extensions tend to get clogged with nasal mucus which reduces the supply of oxygen to the patient. The nasal extensions tend to pop out of the patient's nostrils during sleep removing the entire stream of oxygen from the nostrils of the patient. The shape of the nasal cannula with nasal extensions makes them difficult to clean. The invasive nasal extensions are intimidating to pediatric patients who will often tend to pull the nasal extensions from their noses. A nurse or care giver will often have to reapply the invasive nasal cannula. This can cause the patient discomfort since realigning the nasal cannula will require re-taping of the patient's face to hold the tubes in place.
To overcome the disadvantages associated with a nasal cannula having nasal extensions, a nasal cannula which is non-invasive, i.e. not having nasal extensions extending into the nostrils of the patient, is disclosed in U.S. Pat. No. 4,406,283 issued to Bir. This patent relates to a non-invasive nasal cannula having no portion which intrudes into the nostrils or other sensitive parts of the patient's face. The Bir cannula comprises a piece of flexible tubing having a plurality of apertures. The apertures are circumferentially spaced along the tubing so as to develop a number of ejecting streams of oxygen, at least some of which are directed upwardly and into the region of the nose so that the patient can readily receive an atmosphere of virtually pure oxygen.
There are several advantages to the structure of a non-invasive cannula. For instance, the non-invasive cannula is more comfortable to the patient since the cannula will not dry out the nasal membranes of the patient. The apertures of the non-invasive nasal cannula are less likely to become clogged with nasal mucus, and during sleep there is nothing to disengage from the patient's nose to prevent the oxygen supply from reaching the patient. The non-invasive nasal cannula is less intimidating to pediatric patients so that such a patient tends to leave the non-invasive cannula alone and not pull it away from their face. The non-invasive cannula is care giver friendly since it is easier to line up and allows some leeway in placement which prevents the re-taping of the patient's face to position the cannula.
A major disadvantage of the Bir non-invasive nasal cannula is that only a small percentage of the oxygen stream actually is delivered to the patient's nasal passages. For instance, the plurality of apertures in the Bir cannula allow the oxygen to escape at several angles relative to the patient. Much of the oxygen is vented away from the patient's nasal passages.
Although the aforementioned nasal cannula may function satisfactorily for its intended purpose, there is a need for a non-invasive nasal cannula having all the benefits stated above of a non-invasive cannula but also which directs substantially the entire stream of oxygen toward the patient's nasal passages. The improved non-invasive nasal cannula should be easy to position on the patient's face and have means for remaining in a correct position. The improved non-invasive nasal cannula should make it easy for a care giver to visualize whether the cannula is clean and supplying an appropriate amount of oxygen, and it should be easy to clean if it should become partially or fully clogged. Finally, an improved non-invasive nasal cannula should be especially adapted for use on premature infants to allow a stream of oxygen to be administered to the infant while allowing the infant to be comfortable.